1. Field of the Invention
This invention relates to stacking of wood such as lumber and plywood for drying or other purposes and more particularly, to an automatic stick laying apparatus for positioning spacing sticks on stacked tiers of lumber in selectively spaced relationship to provide proper ventilation between the respective layers or tiers of lumber.
At a very early date it became obvious that lumber must be cured prior to use in order to avoid, or at least minimize, warping due to drying. In the early sawmill days "green" lumber was stacked in "ricks" which defined an inverted "V" configuration, where it was air-dried to reduce the moisture content and provide reasonably straight boards for building purposes. With the development of modern sawmills, the rate of processing and drying or curing of "green" lumber increased to the point that it became impractical and unprofitable to stack lumber in this "rick drying" fashion and other techniques were devised to accomplish this purpose. The lumber is now stacked for kiln drying or air drying and the stacking is preferably accomplished in multiple rows and layers or tiers by inserting between each tier or layer of boards a number of small spacing sticks which keep the layers spaced and provide ventilating passages through the stack to expose both the upper and lower surfaces of the boards in the stack to the drying air. This procedure serves the purpose of processing a large number of boards of selected size in a relatively short period of time, thereby providing more favorable sawmill economics.
2. Description of the Prior Art
The stacking of lumber has been accomplished by various apparatus and techniques in modern times. U.S. Pat. No. 2,928,559, dated Mar. 15, 1960, to D. E. Mosely, details a "Lumber Stacker" which includes a mechanism for receiving boards from a source of supply, gathering the boards in layers and depositing the layers on the stack being formed and further including a mechanism for inserting multiple spacing sticks between each layer as the lumber is stacked, to space the layers in tiers. U.S. Pat. No. 3,352,434, dated Nov. 15, 1967, to W. H. Zuercher, details a "Stick Placer Apparatus". The device features a constant feed of sticks on slats from a removable cartridge to insert the stick between successive layers of a stack of lumber and space the lumber for drying. A "Lumber Spacer and Stick Layer" is detailed in U.S. Pat. No. 4,229,133, dated Oct. 21, 1980, to Charles L. Johnson. The lumber spacer automatically separates lumber in parallel alignment, drops spacer sticks on top of the stacked lumber and subsequently stacks more lumber on top of the spaced sticks. U.S. Pat. No. 4,360,303, dated Nov. 23, 1982, to Alpo Rysti, details a "Method and Apparatus for Locating Spacer Strips Between Layers of Timber Packages". The device positions spacer strips between vertically adjacent layers of timber by locating multiple spacer strips supported by distribution members over the top layer of the timber package and activating multiple depressers, which are operatively associated with a frame structure, downwardly to engage respective spacer strips and guide the strips into position on the top layer of the timber package. U.S. Pat. No. 4,610,360, dated Sep. 9, 1986, to H. Forslund, details an "Installation for Stacking Piles of Lumber Separated by Sticks". The device includes a number of sink compartments adapted to receive various types of lumber and a lumber conveyor designed to bring lumber from a loading point for unsorted lumber to the sink department. The lumber conveyor also transports sticks to tile sink compartment for separation of the lumber in stacked tiers. A "Sticker Placer Apparatus" is detailed in U.S. Pat. No. 4,801,233, dated Jan. 31, 1989, to Edward Ritola. The apparatus includes multiple inclined sticker feed pockets designed to hold facing sticks and adapted to displace one stick at a time from the mouth of the sticker pocket to a variable height of lumber beneath the pocket. U.S. Pat. No. 4,810,152, dated Mar. 7, 1989, to Larry A. Gillingham, et al, details a "Sticker Positioning Apparatus for Use With Lumber Stacker". This apparatus includes an unscrambling conveyor that feeds six spacers from a bulk supply to a crowder feed conveyor, in order to supply sticks to a timed release mechanism. The release mechanism is operated by a cam device to sequentially present the individual spacer sticks in timed fashion to an endless distribution conveyor, where they are moved to the top of a lumber stack and accurately positioned in spaced relationship on the lumber. "A Stick Delivery Apparatus" is detailed in U.S. Pat. No. 4,378,803, dated Nov. 7, 1989, to Wade Q. Whiddon. The device includes a frame, a stick conveyor supported on the frame for movement between a stick supply station and a stick transfer station. The stick conveyor includes structure for transporting sticks from the supply station and for delivering the sticks to the transfer station in spaced, parallel relationship and additional apparatus is provided for replacing the sticks on stacked lumber beneath the frame.
It is an object of this invention to provide an automatic stick laying apparatus for mounting over stacks of lumber, plywood or pressboard and automatically placing spacing sticks on each successive layer or tier of lumber, plywood or pressboard in preselected spaced relationship to facilitate drying or other disposition of the vertically spaced lumber, plywood or pressboard.
Another object of this invention is to provide an automatic stick laying apparatus which is characterized by a fixed frame, an accumulator mounted on the fixed frame for receiving and accumulating multiple spacing sticks, spaced drop gates attached to the fixed frame below the accumulator, a carriage assembly movably mounted on the fixed frame and fitted with parallel chain channels provided with positioner chains having spaced positioner chain cleats for receiving spacing sticks from the accumulator and drop gates and multiple, spaced diverter assemblies attached to the chain channels for sequentially displacing the spacing sticks on selected ones of the positioner chain cleats and relocating the spacing sticks in selected spaced relationship on successive stacks of lumber located beneath the stick laying apparatus by sequential limited advancement of the positioner chains.
Yet another object of this invention is to provide an automatic stick laying apparatus which is characterized by a fixed frame, an accumulator mounted on the fixed frame for receiving and accumulating multiple spacing sticks, spaced drop gates attached to the fixed frame below the accumulator, a carriage assembly movably mounted on the fixed frame and fitted with parallel chain channels provided with positioner chains having spaced positioner chain cleats for receiving spacing sticks from the accumulator and drop gates and multiple, spaced diverter assemblies attached to the chain channels for sequentially displacing the spacing sticks from selected ones of the positioner chain cleats and relocating the spacing sticks in selected spaced relationship on successive stacks of lumber located beneath the stick laying apparatus.
Still another object of this invention is to provide an automatic stick laying apparatus which is characterized by a fixed frame, an accumulator mounted on the fixed frame for receiving and accumulating multiple spacing sticks, spaced drop gates attached to the fixed frame below the accumulator, a carriage assembly movably mounted on the fixed frame and fitted with parallel chain channels provided with positioner chains having spaced positioner chain cleats for receiving spacing sticks from the accumulator and drop gates and multiple, spaced diverter assemblies attached to the chain channels for sequentially pivoting into the path of selected ones of the spacing sticks and relocating the spacing sticks in selected spaced relationship on successive stacks of lumber located beneath the stick laying apparatus by advancement of the positioner chains.
A still further object of this invention is to provide an automatic, computer-operated stick laying apparatus which utilizes a pair of vertically adjustable, horizontal, endless accumulator chains mounted on a fixed frame and fitted with spaced accumulator chain cleats for accumulating a supply of spacing sticks from a stick supply device, drop gates mounted on the fixed frame beneath the accumulator, a pair of vertically adjustable positioner chain channels horizontally mounted on the fixed frame and receiving a pair of spaced endless positioner chains provided with spaced positioner chain cleats and fitted with a pair of companion advancing chains, for receiving spacing sticks in a selected sequence from the accumulator through the drop gates and carrying the spacing sticks into proper positions above stacked tiers of lumber located beneath the stick laying apparatus and further including spaced diverter assemblies located between the positioner chain channels for sequentially displacing the spacing sticks on selected positioner chain cleats to facilitate sequential limited advancement of the positioner chains and positioning the displaced spacing sticks in a selected spacing on successive layers of lumber to vertically space the layers of lumber for drying purposes.
Another object of this invention is to provide a method for automatically placing spacing sticks in a selected pattern on successive tiers of stacked wood products such as lumber, plywood or the like, which method includes the steps of spacing the spacing sticks in a horizontally-positioned, endless chain accumulator, sequentially dropping the spacing sticks through adjacent gates to locations between parallel sets of spaced positioner chain cleats attached to a pair of horizontal endless positioner chains located above the lumber, locating the spacing sticks over the lumber by operation of the positioner chains, lowering the positioner chains and spacing sticks to a point immediately above the top layer of lumber, causing selected spacing sticks to be displaced to preselected positions on the positioner chain cleats by operation of spaced diverter assemblies, advancing the positioner chains to deposit the spacing sticks in the selected pattern on the lumber, repositioning the diverter assemblies into the prediverting configuration and raising the positioner chains to receive additional spacing sticks from the accumulator.
A further object of this invention is to provide a method for placing spacing sticks on tiers of lumber in a selected pattern or spacing, wherein the spacing sticks are loaded from a stick supply apparatus on a horizontal accumulator between adjacent sets of parallel accumulator chain cleats, the sticks are then selectively distributed to empty positioner chain cleats located on a pair of horizontal endless positioner chains through spaced drop gates, the positioner chains next automatically locate the spacing sticks in proper orientation over the lumber, the carriage assembly is then lowered to a point immediately over the top layer of lumber, where preselected numbers of spacing sticks are displaced on corresponding chain cleats by operation of selected diverter assemblies, the positioner chains are then advanced a short distance to place the sticks on the lumber in the selected pattern, the diverter assemblies are repositioned and the carriage assembly is raised to receive additional spacing sticks.
These and other objects of the invention are provided in a new and improved automatic stick laying apparatus and method for laying spacing sticks on successive tiers of lumber, which apparatus includes a fixed frame and a carriage assembly slidably mounted on the fixed frame above an area where lumber is to be stacked. The fixed frame further supports a stick supply apparatus which interfaces with a pair of horizontally-spaced, endless accumulator chains fitted with accumulator chain cleats for accumulating spacing sticks and multiple, spaced, programmable controller-operated, cylinder-actuated drop gates located beneath the accumulator chains. A pair of spaced, parallel chain channels, fitted with corresponding endless positioner chains, are located on the carriage assembly beneath the accumulator chains and drop gates and the positioner chains are provided with spaced chain cleats for sequentially receiving the spacing sticks by operation of the drop gates. Advancing chains are also provided in the carriage assembly and operate with the positioner chains and a pair of rubber discs to seat the spacing sticks on the positioner chain cleats for transporting the spacing sticks to preselected positions over the lumber to be stacked. Multiple cylinder-actuated diverter assemblies, mounted in spaced relationship on the positioner chain channels and controlled by programmable controller, computer, or alternative control devices, operate to sequentially displace preselected spacing sticks on corresponding positioner chain cleats responsive to lowering of the carriage assembly, after which the positioner chains are advanced in sequence to deposit the spacing sticks in spaced relationship on the underlying tiers of lumber to vertically space the lumber in stacked layers. Alternatively, tile programmable controller may be programmed to cause the contact legs of selected diverter assemblies to pivot downwardly and displace corresponding spacing sticks from the respective sets of positioner chain cleats. Further in the alternative, selected diverter assemblies may be directed by the programmable controller to pivot the respective contact legs into the path of the corresponding spacing sticks to displace the spacing sticks from the positioner chain cleats by advancement of the positioner chains.